Bloob grouping and

 Blood grouping is based on type of antigen
present on the red blood cells.
 There are more than 300 blood group
systems but ABO and Rh(Rhesus) are of
importance from clinical point of view.
 Other blood group systems are MNS ,
Lutheran , Kell , Lewis , Duffy , Kidd etc.

 Discovered by Karl Landsteiner in 1900.
 The red cells contain different types of
Antigen(Agglutinogen) while plasma
contains antibody(Agglutinins)
LANDSTEINER’S LAW
If an antigen(Ag) is present on a patient’s
RBC, the corresponding antibody(Ab)
should not be present in patient’s plasma
under normal condition.

Methods of blood grouping:
1)Slide method – forward
typing(unknown antigen with
known antibody)
2)Tube method – both forward and
backward typing(known antigen
with unknown antibody) – better
method

REQUIREMENTS:
1)3 slides
2)Antisera A , B
3) Blood samples

PROCEDURE:
1) Take 2 clean slides and mark them 1, 2 .
2) Put one drop of antisera A on slide 1 ,
one drop of antisera B on slide 2.
3) Add one drop of blood to each and mix
well with stick
4) Wait for 5 min and observe.

OBSERVATION:
 If any agglutination occurs it is visible
with naked eyes as dark reddish clumps of
different sizes.
 If agglutination is minimal it can be
confirmed by examining it under
microscope.

INTERPRETATION:
1)Agglutination with antisera A not with
antisera B – group A
2)Agglutination with antisera B not with
antisera A – group B.
3)Agglutination with both
antisera A and B – group AB
4)No agglutination in any slide – group O

Universal donor – blood group O as no
Ag so no agglutination.
Universal receipient – blood group AB
as both A and B Ags present so
agglutination occurs in both as no
Abs present in serum.

Rh TYPING
Rh blood group system is second in
significance to ABO system.
Consists of over 50 related Ags.
Genes that control the system are
autosomal codominant present on
chromosome 1.
Polymorphic(more than one
phenotype)
Important genes are D,C,E,c,e.

HISTORY:
1939 – Levine and Stetson defined D
antigen(Rh factor)
1949 – Landsteiner and Weiner
discovered anti Rh (named after
Rhesus monkey)

Rh antigen frequency:
D Antigen – 85%
C Antigen – 70%
c Antigen – 80%
E Antigen – 30%
e Antigen – 98%

Rh antigen is encoded by 2 genes –
RHD – encodes for D
RHCE – encodes for Cc and Ee.
Rh positive:
Rh positive cells express D Ag on the
red cell surface.These constitute
85% of the population of which 40%
are DD and 60% are Dd.

Rh negative:
There is absence of D antigen.These
individuals constitute 17% of
population.
Ce and Ee antigen:
These are weak antigens and
therefore risk of sensitisation is less
than that of D antigen.

Rh antibody:
Unlike ABO system there is no
naturally occuring antibodies against
Rh antigens in Rh negative
individuals.
Immune Abs:
Rh Abs develp against Rh Ag after
exposure to Rh Ags following
transfusion or prenancy.Most of
these are IgG type and can be
detected by enzyme treatment or
coomb test(antiglobulin test)

SIGNIFICANCE:
Rh incompartibility results in
haemolytic tranfusion reaction.
Haemolytic disease of newborn.

TECHNIQUES:
1) slide method
2)Tube method

SLIDE METHOD:
 Place one drop of anti D on slide.
 Add one drop of blood and mix
well with stick
 Wait for 5 min and observe.
RESULT:
 Agglutination indicates Rh positive
blood samples.

BOMBAY blood group:
Expression of A and B genes appears
to be dependent on gene H.
Bombay phenotype are individuals
who lack H gene(genotype h),
therefore no H substance is formed
and no A/B Ags develops even
though individuals may possess A/B
genes.
They test as group O and possess
anti A ,anti and anti H antibodies.

IMPORTANCE OF BLOOD
GROUPING:
In blood transfusion
Haemolytic disease of newborn.
Paternity dispute
Medicolegal issues
Immunology,genetics,anthropology
Susceptibility to various
disease(blood group O – peptic ulcer
Blood group A – gastric ulcer)

Also known as compartibility testing.
It is the most important test before
a blood transfusion is given.
The primary purpose of cross
matching is to detect ABO
incompartibilities between donor
and receipient .
This is carried out to prevent
transfusion reactions by detecting
Abs in receipient’s serum.

Two main functions of cross
matching test:
1)It is a final check of ABO
incompartibility between donor and
receipient.
2)It may detect presence of Ab in
patient’s serum that will react with
Ags on donor RBCs but that was not
detected in Ab screening because
the corresponding Ag was lacking
from the screening cell.

Cross matching test can be
1) major
2) minor
MAJOR CROSS MATCH TEST:
Mixing the patient’s serum with
donor RBCs.

MINOR CROSS MATCH TEST:
 mixing the donor’s plasma with
patient’s RBCs.
It is completely eliminated in most
blood banks, because donor samples
are screened beforehand for the
more common Abs.

Types:
1) saline cross match - detects IgM
Abs
2) albumin technique - detects IgG
Abs
3) enzyme technique - detects IgG
and some IgM Abs.
4) antiglobulin test or coomb test –
detects IgG Abs.

PROCEDURE:
Take 1 drop of receipient’s serum in a
small test tube.
Add 5% saline suspension of donor’s
RBC to receipient’s serum.
Mix the two.
Incubate at 370c for 30 mins.
Centrifuge at 3000rpm for 1 min.
Dislodge the cells gently and examine
macroscopically and microscopically
for agglutination or lysis.

RESULT:
Agglutination or haemolysis absent –
match
Agglutination or haemolysis present-
mismatch

SCREENING TESTS BEFORE BT:
Malaria
Syphilis
HBV
HCV
HIV

Bloob grouping and

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